The 18-year-old joins from Chelsea for an undisclosed fee.
Malakai started his youth career at Barnet before joining the Premier League giants. He also had a spell on loan at Derby County.
Speaking to barnetfc.com, Malakai stated “I’m happy to be home. I’ve missed being here, it really is like a home to me.
“Rossi has told me to remain humble and come here to work hard, nothing will ever be given to me. I have to go out there and bring some great stuff to the pitch.
“I’m a quick forward who likes to get in behind, take on my man and create chances for other people. “
Speaking about his Deadline Day signing, Rossi has said “It’s a great coup to sign Malakai from Chelsea. I know the player well and am delighted to be working with him again.
“He will add to our attacking front line with goals and pace. He will also learn and develop with the Under 21s throughout the week.”